U.S. patent application number 10/474716 was filed with the patent office on 2004-12-02 for luminescent reaction measurement device.
Invention is credited to Kamiya, Akifumi, Suzuki, Yoshihito.
Application Number | 20040241777 10/474716 |
Document ID | / |
Family ID | 18965341 |
Filed Date | 2004-12-02 |
United States Patent
Application |
20040241777 |
Kind Code |
A1 |
Suzuki, Yoshihito ; et
al. |
December 2, 2004 |
Luminescent Reaction Measurement Device
Abstract
Light resulting from chemiluminescence inside a reaction chamber
4 is transmitted through a light transmitting window 3, a large
part of the light is made incident on a photoelectric surface 71 of
a photomultiplier tube 2 to generate photoelectrons, and these
photoelectrons are successively multiplied by surfaces 79 at one
side of dynodes 78a, 78, and 78b. Meanwhile, a part of the light
that is not made incident on photoelectric surface 71 is made
incident on and reflected by a surface 77 at the other side of
dynode 78a, returned to reaction chamber 4 via light transmitting
window 3, reflected further by light reflecting surfaces 40 and 41
inside reaction chamber 4, emitted again from light transmitting
window 3, and made incident on photoelectric surface 71 of
photomultiplier tube 2 to generate and multiply photoelectrons in
the same manner as the above. The amount of light made incident on
photoelectric surface 71 is thus increased by the amount
corresponding to the reflection at surface 77 at the other side of
the dynode, thereby enabling detection of light caused by weak
chemiluminescence.
Inventors: |
Suzuki, Yoshihito;
(Hamamatsu-shi, JP) ; Kamiya, Akifumi;
(Hamamatsu-shi, JP) |
Correspondence
Address: |
MORGAN LEWIS & BOCKIUS LLP
1111 PENNSYLVANIA AVENUE NW
WASHINGTON
DC
20004
US
|
Family ID: |
18965341 |
Appl. No.: |
10/474716 |
Filed: |
July 23, 2004 |
PCT Filed: |
April 11, 2002 |
PCT NO: |
PCT/JP02/03626 |
Current U.S.
Class: |
435/8 ;
435/287.1 |
Current CPC
Class: |
G01N 21/76 20130101;
H01J 43/20 20130101 |
Class at
Publication: |
435/008 ;
435/287.1 |
International
Class: |
C12Q 001/66; C12M
001/34 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 12, 2001 |
JP |
2001-114239 |
Claims
1. A luminescent reaction measurement device, which makes a sample
gas and an oxidizing gas react in a reaction chamber and detects,
by means of a light detector, the intensity of the light resulting
from the chemiluminescence that occurs during said reaction,
wherein inner surfaces of said reaction chamber is arranged to be
light reflecting, and said reaction chamber is equipped with a
light transmitting window that makes said light due to
chemiluminescence in said reaction chamber be emitted therefrom
towards said light detector that is installed outside said reaction
chamber, said light detector is a side-on type photomultiplier
tube, comprising a cylindrical container, into which said emitted
light due to chemiluminescence enters through the peripheral
surface, a reflecting type photoelectric surface for
photoelectrically converting said light due to chemiluminescence
that has entered inside said container and generating
photoelectrons, and plurality of dynodes, each having, on a surface
at one side, a secondary electron emission surface that emits
secondary electrons upon incidence of electrons and thereby
successively multiplying and outputting said photoelectrons, and at
least one of said dynodes receives, on the surface at the other
side, said light due to chemiluminescence that has entered through
said peripheral surface and reflects it toward said light
transmitting window of said reaction chamber.
2. The luminescent reaction measurement device as set forth in
claim 1, wherein the surface at the other side of the dynode that
receives and reflects said light due to chemilumiescence is formed
of gold.
3. (canceled)
4. (canceled)
5. The luminescent reaction measurement device as set forth in
claim 1, wherein the dynode that receives and reflects said light
due to chemiluminescence by the surface of the other side is a
first dynode that first receives the photoelectrons generated by
said photoelectric surface.
6. The luminescent reaction measurement device as set forth in
claim 2, wherein the dynode that receives and reflects said light
due to chemiluminescence by the surface of the other side is a
first dynode that first receives the photoelectrons generated by
said photoelectric surface.
7. The luminescent reaction measurement device as set forth in
claim 1, wherein said photomultiplier tube is equipped with a
cooling device that cools said photoelectric surface.
8. The luminescent reaction measurement device as set forth in
claim 2, wherein said photomultiplier tube is equipped with a
cooling device that cools said photoelectric surface.
9. The luminescent reaction measurement device as set forth in
claim 5, wherein said photomultiplier tube is equipped with a
cooling device that cools said photoelectric surface.
10. The luminescent reaction measurement device as set forth in
claim 6, wherein said photomultiplier tube is equipped with a
cooling device that cools said photoelectric surface.
Description
TECHNICAL FIELD
[0001] This invention concerns a luminescent reaction measurement
device, which makes a sample gas react with an oxidizing gas and
thereby emits chemiluminescence and detects the light resulting
from this luminescence.
BACKGROUND ART
[0002] In recent years, there has been an increasing demand for
concentration measurement devices of the type, which makes nitrogen
monoxide, etc., in a sample gas undergo a chemical reaction with
ozone or other oxidizing gas and measures the concentration of the
nitrogen monoxide, etc., in the sample gas based on the intensity
of the light due to chemiluminescence resulting from the reaction.
With such a device, it is possible, for example, to measure the
concentration of nitrogen monoxide in the expired air of an
asthmatic patient in order to monitor the effects of treatment, and
to measure the concentration of nitrogen monoxide in the exhaust
gas of an automobile in order to tackle environmental problems.
[0003] Such a concentration measurement device requires a
luminescent reaction measurement device that measures the intensity
of the light due to chemiluminescence, and a luminescent reaction
measurement device, such as that disclosed in Japanese Unexamined
Patent Publication (Tokukai) No. Hei 7-333150, is popularly used.
This device is equipped with a reaction tank, having an indented
part formed therein, and a photodiode, having a light receiving
surface and serving as a light detector, and this photodiode is
fitted into the indented part of the reaction tank so that a
reaction chamber of a predetermined space is formed by the light
receiving surface and the inner surface of the indented part of the
reaction tank.
[0004] With this luminescent reaction measurement device, for
example, nitrogen monoxide is made to react with ozone in the
reaction chamber, the intensity of the light resulting from
chemiluminescence is detected by the light receiving surface of the
photodiode and an electrical signal according the detection is
output.
DISCLOSURE OF THE INVENTION
[0005] Improvement of the detection sensitivity of luminescent
reaction measurement devices is being desired recently to enable
the detection of more dilute gases. However, with the prior-art
luminescent reaction measurement device, the light detector forms a
part of the wall of the reaction chamber and thus when the light
detector is cooled to reduce the noise of the light detector, the
temperature of the interior of the reaction chamber drops, thus
causing the reaction rate of the chemiluminescence to drop and
preventing improvement of the detection sensitivity. Also, if the
reaction chamber is made large to increase the amount of light due
to chemiluminescence and this is detected by a large light
detector, the background noise increases as a result of making the
light detector large and furthermore, the heat generated by the
light detector itself increases, making the cooling of the light
detector difficult and thus preventing improvement of the detection
sensitivity.
[0006] This invention has been made to resolve the above problems
and an object thereof is to provide a luminescent reaction
measurement device that can measure light due to chemiluminescence
at high sensitivity by a simple arrangement.
[0007] This invention provides in a luminescent reaction
measurement device, which makes a sample gas and an oxidizing gas
react in a reaction chamber and detects, by means of a light
detector, the intensity of the light resulting from the
chemiluminescence that occurs during the reaction, a luminescent
reaction measurement device characterized in that the reaction
chamber is arranged with its inner surfaces being light reflecting
and is equipped with a light transmitting window that makes the
light due to the chemiluminescence in the reaction chamber be
emitted towards the light detector that is installed outside the
abovementioned reaction chamber, the light detector is a side-on
type photomultiplier tube, comprising a cylindrical container, into
which the emitted light due to chemiluminescence enters from the
peripheral surface, a reflecting type photoelectric surface,
photoelectrically converting the light due to chemiluminescence
that enters inside the abovementioned container and generating
photoelectrons, and a plurality of dynodes, each having, on a
surface at one side, a secondary electron emission surface that
emits secondary electrons upon incidence of electrons and thereby
successively multiplying and outputting photoelectrons, and at
least a part of the dynodes receives, on the surface at the other
side, the light due to chemiluminescence that enters from the
peripheral surface and reflects the light toward the light
transmitting window of the reaction chamber.
[0008] With this invention's luminescent reaction measurement
device, the light resulting from chemiluminescence in the reaction
chamber is transmitted through the light transmitting window and a
large part of the light is made incident on the photoelectric
surface of the photomultiplier tube to cause the generation of
photoelectrons, and these photoelectrons are output upon being
successively multiplied by the surfaces at one side of the dynodes.
Meanwhile, a part of the light is made incident on the surfaces at
the other side of the dynodes without being made incident on the
photoelectric surface and this light is reflected by the surfaces
at the other side of the dynodes, returns to the reaction chamber
via the light transmitting window, is reflected furthermore by the
light reflecting surface inside the reaction chamber, emitted again
from the light transmitting window, made incident on the
photoelectric surface of the photomultiplier tube, and
photoelectrons are generated, multiplied, and output in like wise
manner. The amount of light made incident on the photoelectric
surface is thus increased by the amount reflected by the surfaces
at the other side of the dynodes to enable the detection of light
caused by weak chemiluminescence.
[0009] Also, since the photomultiplier tube, which is the light
detector, is separated from the reaction chamber and the
photomultiplier tube can be cooled to reduce the noise generated in
the photomultiplier tube without lowering the temperature of the
interior of the reaction chamber, the detection of weaker
chemiluminescence is enabled.
[0010] Here, the surfaces at the other side of the dynodes that
receive and reflect the light due to chemiluminescence are
preferably formed of gold.
[0011] The surfaces of the other side of the dynodes are thus made
high in reflection efficiency and the amount of light returning to
the reaction chamber is increased to enable the detection of light
caused by weak chemiluminescence to be carried out more
favorably.
[0012] Also, the dynode that receives and reflects the light due to
chemiluminescence by the surface of the other side is preferably a
first dynode that first receives the photoelectrons generated by
the photoelectric surface. Reflection of light is thereby carried
out favorably.
[0013] Also, the photomultiplier tube is preferably equipped with a
cooling device that cools the photoelectric surface. Cooling of the
photoelectric surface is thereby carried out efficiently for
reduction of noise and detection of weak chemiluminescence is
carried out even more favorably.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a general perspective view showing a luminescent
reaction measurement device of an embodiment.
[0015] FIG. 2 is a sectional view of the reaction module in FIG.
1.
[0016] FIG. 3 is a side view partly in section of the luminescent
reaction measurement device of FIG. 1.
[0017] FIG. 4 is a horizontal sectional view of the luminescent
reaction measurement device of FIG. 1.
[0018] FIG. 5 is a front view of the luminescent reaction
measurement device of FIG. 1.
BEST MODE FOR CARRYING OUT THE INVENTION
[0019] A favorable embodiment of a luminescent reaction measurement
device by this invention will be described in detail with reference
to the attached drawings. In the description using the drawings,
the same or corresponding elements shall be provided with the same
symbol and redundant description shall be omitted.
[0020] FIG. 1 is a general perspective view showing a luminescent
reaction measurement device of an embodiment. Luminescent reaction
measurement device 1 of this embodiment measures the concentration
of nitrogen monoxide contained in a sample gas, and for this
purpose, makes the nitrogen monoxide in the sample gas react with
ozone, which serves as an oxidizing gas, to make chemiluminescence
occur and measures the intensity of the light resulting from this
luminescence.
[0021] Luminescent reaction measurement device 1 is equipped with a
reaction module 20, which is equipped in turn with a reaction
chamber 4 in which the nitrogen monoxide in the sample gas is made
to react with ozone, and a light measurement module 21, onto which
reaction module 20 is installed and which measures the intensity of
the light of the chemiluminescence resulting from the reaction in
reaction chamber 4 of reaction module 20.
[0022] As shown in FIG. 2, reaction module 20 is equipped with a
reaction cell 5, having an indented part 63 formed therein, and a
lid plate 6, which serves as a lid for indented part 63 of reaction
cell 5 and forms reaction chamber 4 by closing indented part
63.
[0023] Reaction cell 5 has an open rectangular tube part 35 formed
so as to protrude from a surface at one side (surface at the
opposite side of lid plate 6) at the center of a rectangular plate
of predetermined thickness. At the end of rectangular tube part 35,
a red filter (light transmitting window) 3, having the same outer
diameter as rectangular tube part 35 and closing the abovementioned
end, is adhered by means of an adhesive agent 36. Indented part 63
is formed by red filter 3 and the inner walls of rectangular tube
part 35.
[0024] Red filter 3 functions as a long-wavelength transmitting
filter that is suitable for the spectrum of the chemiluminescence
and emits diffuse light due to the chemiluminescence that occurs
inside reaction chamber 4 to the exterior (left side of the
figure).
[0025] As adhesive agent 36, an adhesive agent, which by itself
does not give rise to a gas that causes a luminescent reaction,
does not extinguish the luminescent reaction, and is not degraded
by the oxidizing gas, etc., is favorable, and for example, a
silicon adhesive agent may be used.
[0026] On the inner walls of rectangular tube part 35 is formed a
gold plating layer 40, which improves the light reflecting property
and prevents corrosion due to the oxidizing gas.
[0027] Meanwhile, lid plate 6 is a rectangular plate of
substantially the same size as reaction cell 5, and at a part that
covers indented part 63 of reaction cell 5 and becomes a part of
the inner walls of reaction chamber 4, a gold plating layer 41 is
formed in the same manner as with the inner walls of rectangular
tube part 35 of reaction cell 5. Also at a surface of lid plate 6
that contacts reaction cell 5 at the outer side of reaction chamber
4 a groove 37 for fixing an O-ring is formed in a ring-like manner.
Furthermore, at a central part of the rear surface of lid plate 6,
a box-like protruding part 39 is formed, and in this protruding
part 39 are formed four gas ports 27, 28, 29, and 30, which
respectively put the interior of reaction chamber 4 in
communication with the exterior.
[0028] As shown in FIG. 1, light measurement module 21 has a long,
box-shaped case 50, and this box-shaped case 50 is equipped with a
side plate 50a onto which reaction module 20 is installed. As shown
in FIG. 3 and FIG. 4, in the interior of case 50, a photomultiplier
tube 2, which detects light due to chemiluminescence from reaction
chamber 4 of reaction module 20, is erected close to side plate
50a.
[0029] This photomultiplier tube 2 shall now be described in
detail. Photomultiplier tube 2 has a cylindrical glass bulb 75 and
is equipped with a main detector body 102 inside this glass bulb
75. Main detector body 102 mainly comprises a lattice electrode 70,
through which light can be transmitted, a reflecting type
photoelectric surface 71, which generates photoelectrons by
photoelectric conversion of the light due to chemiluminescence that
is made incident upon being transmitted successively through the
peripheral surface of glass bulb 75 and lattice electrode 70, a
substrate 72, which holds this photoelectric surface 71 on its
surface, a plurality of stages of dynodes 78, each having a
secondary electron emission surface 79, which emits secondary
electrons upon incidence of electrons, formed on a surface at one
side and successively multiplying, at this surface at one side, the
photoelectrons that are emitted from photoelectric surface 71 and
guided by lattice electrode 70, an anode 80, which collects the
multiplied photoelectrons and takes them out as an output signal,
and a plurality of pin terminals 81 for applying high voltage
successively across intervals between lattice electrode 70 and
anode 80 as shown in FIG. 3. This photomultiplier tube 2 is a
so-called side-on type photomultiplier tube.
[0030] As shown in FIG. 4, of the dynodes 78 that comprise this
photomultiplier tube 2, a first dynode 78a, onto which the
photoelectrons generated at photoelectric surface 71 are made
incident first, is curved in a concave manner with respect to
photoelectric surface 71, the surface opposing photoelectric
surface 71 is made the secondary electron emission surface 79, and
the rear surface (surface at the other side) has a gold plating
layer (gold) 77 formed thereon.
[0031] Also as shown in FIG. 3, with photomultiplier tube 2, a
metal conductive plate 84 is installed so as to close the open end
at the upper side of glass bulb 75, a setting base 83 of good
thermal conductivity is set above conductive plate 84, a Peltier
element (cooling device) 76, which cools setting base 83 by the
Peltier effect, is installed above setting base 83, and radiating
fins 86, which radiate the heat of Peltier element 76, are equipped
above Peltier element 76. On the roof plate of case 50 above
radiating fins 86 is installed a cooling fan 59, which cools the
radiating fins 86. At the lower surface of conductive plate 84 is
equipped with a contact piece 82 of good thermal conductivity that
connects conductive plate 84 with substrate 72 that holds
photoelectric surface 71.
[0032] Via substrate 72, contact piece 82, conductive plate 84, and
setting base 83, photoelectric surface 71 is cooled efficiently by
Peltier element 76, and photoelectric surface 71 is thus maintained
adequately at a low temperature so that the generation of noise due
to thermions is reduced and the sensitivity is improved. The energy
required to cool photoelectric surface 71 is also reduced and the
waiting time for cooling is also shortened.
[0033] Since photoelectric surface 71 is cooled directly without
cooling the entirety of photomultiplier tube 2, the temperature of
the interior of reaction chamber 4 is not lowered even if
photomultiplier tube 2 and reaction chamber 4 are positioned close
to each other, and since photomultiplier tube 2 and reaction
chamber 4 can be positioned closer to each other, detection of
luminescence at higher sensitivity is enabled.
[0034] Also as shown in FIG. 3 and FIG. 4, on side plate 50a of
light measurement module 21, a rectangular tube part 51, which
protrudes towards the inner side of case 50, is formed at a part
opposing main detector body 102 of photomultiplier tube 2 near the
center of side plate 50a.
[0035] On the inner surface of this rectangular tube part 51 is
equipped with a rectangular-tube-shaped entry port 55, the inner
diameter of which is made the same as the outer diameter of
rectangular tube part 35 of reaction cell 5 of reaction module 20,
and which guides the light due to chemiluminescence to
photomultiplier tube 2, is formed by an insulating material and
holds glass bulb 75.
[0036] Reaction module 20 is arranged by inserting red filter 3 and
rectangular tube part 35 of reaction cell 5 in entry port 55 of
light measurement module 21 and overlapping lid plate 6, having an
O-ring 38 inserted inside groove 37 for sealing, onto the rear
surface of reaction cell 5, and this reaction module 20 is fixed by
bolts 58 onto side plate 50a of case 50 of light measurement module
21.
[0037] Here, with photomultiplier tube 2, the installation angle in
the peripheral direction is set as shown in FIG. 4 so that first
dynode 78a does not block the path of light that is made incident
on photoelectric surface 71 from reaction chamber 4 and the curving
part at the red filter 3 side of gold plating layer 77 on the rear
surface of first dynode 78 opposes red filter 3, thereby enabling
the light entering from reaction chamber 4 to be received
efficiently by photoelectric surface 71 and enabling the light
received by a part of the rear surface of first dynode 78a to be
reflected efficiently towards red filter 3. The angle a of
photoelectric surface 71 with respect to the normal to side plate
50a is preferably set in the range of 61 to 66.degree., and in this
case, photomultiplier tube 2 is positioned so that the line joining
the pin of fourth dynode 78b and the center of photomultiplier tube
2 is approximately 90.degree. with respect to the normal to side
plate 50a.
[0038] The inner diameter in the horizontal direction of
rectangular tube part 35 of reaction cell 5 (the inner diameter
shown in FIG. 4) is set to a wide diameter in order to enable
adequate incidence of light from reaction chamber 4 onto
photoelectric surface 71 and a part of the rear surface of first
dynode 78a, and for the same reason, the inner diameter in the
vertical direction (the inner diameter shown in FIG. 3) is set
greater than or equal to the height of the effective area of
photoelectric surface 71 and first dynode 78a.
[0039] The protruding length (the length shown in FIG. 3 and FIG.
4) of rectangular tube part 35 is set so that in the state in which
rectangular tube part 35 is mounted inside entry port 55, the outer
surface of red filter 3 is positioned close to glass bulb 75 of
photomultiplier tube 2. By thus bringing reaction chamber 4 and
photomultiplier tube 2 close to each other, the light due to
chemiluminescence, which arises inside reaction chamber 4 and
becomes diffuse light, is restrained from attenuating due to
diffusion, etc., along the optical path and is made incident
efficiently onto photomultiplier tube 2.
[0040] Red filter 3 is fixed onto reaction cell 5 using adhesive
agent 36, and thus in comparison to a case where red filter 3 is
fixed by a bolt and an O-ring, etc., the securing of space, etc.,
for the strutting of a bolt and for a groove for an O-ring is made
unnecessary. Photomultiplier tube 2 and red filter 3 can thus be
positioned close to each other and the diffusion of light is
restrained to improve the efficiency of convergence and the
sensitivity. Experiments by the present inventor have shown that in
comparison to cases where red filter 3 is installed using an O-ring
and a bolt, etc., without use of adhesive agent 36, luminescent
reaction measurement device 1 of the present embodiment is
increased by 60% or more in signal amount.
[0041] As shown in FIG. 5, gas ports 27 to 30 are connected
respectively to a nitrogen monoxide introduction tube 7 for
introducing sample gas, containing nitrogen monoxide gas, into
reaction chamber 4, an ozone introduction tube 8 for introducing
ozone into reaction chamber 4, a gas exhaust tube 9 for exhausting
the gas after reaction inside reaction chamber 4, and a pressure
measurement tube 10 for detection of the pressure inside reaction
chamber 4.
[0042] As shown in FIG. 1, ozone introduction tube 8 is connected
to an ozone generating device 12, gas exhaust tube 9 is connected
via a flow regulating valve 15 to a suction pump 13, and pressure
measurement tube 10 is connected to a pressure sensor 14. Since the
exhaust gas exhausted from gas exhaust tube 9 may be hazardous to
the human body in some cases, it is detoxified by being passed
through an activated carbon column, etc., and thereafter released
to the atmosphere.
[0043] Luminescent reaction measurement device 1 of the present
embodiment is arranged as described above. The actions of
luminescent reaction measurement device 1 shall luminescent
reaction measurement device 1 is applied as a device for measuring
the concentration of nitrogen monoxide in the expired air of an
asthmatic patient shall be described.
[0044] First, voltage is applied to main detection body 102 of
photomultiplier tube 2 to set up a state in which detection of
light is enabled and Peltier element 76 and cooling fan 59 are
driven to cool photoelectric surface 71 of photomultiplier tube 2.
Ozone from ozone generating device 12 is then introduced via ozone
introduction tube 8 into reaction chamber 4 and a patient's expired
air that contains nitrogen monoxide is introduced into reaction
chamber 4 via nitrogen monoxide introduction tube 7.
[0045] At this point, in reaction chamber 4, the nitrogen monoxide
in the expired air and the ozone undergo the chemical reaction
expressed by the following formula and cause chemiluminescence.
Here, NO.sub.2* indicates nitrogen dioxide in an excited state.
NO+O.sub.3.fwdarw.NO.sub.2*+O.sub.2
NO.sub.2*.fwdarw.NO.sub.2+h.nu.
[0046] The light due to this chemiluminescence is then transmitted
through red filter 3 and emitted towards photomultiplier tube 2
directly or after being reflected by gold plating layers 40 and 41
on the wall faces of reaction chamber 4. Suction pump 13 is
activated to continuously exhaust the gas resulting from this
reaction out of the system via gas exhaust tube 9. In this process,
flow regulating valve 15 is operated to adjust the exhaust rate so
that the amount of light emitted in reaction chamber 4 is
maximized.
[0047] At this point, a large part of the light that enters
photomultiplier tube 2 is made directly incident on photoelectric
surface 71. The incident light then undergoes photoelectric
conversion at photoelectric surface 71 to become photoelectrons,
and these photoelectrons are made incident on the secondary
electron emission surface 79 side of the surface of first dynode
78a and multiplied in the form of emission of secondary electrons,
which are furthermore multiplied successively by other dynodes 78
and then collected as an output signal at anode 80, thereby
providing an output that is in accordance to the luminous
intensity.
[0048] Meanwhile, the light that is not made directly incident on
photoelectric surface 71 is made incident on a part of gold plating
layer 77 at the rear surface of first dynode 78a, is reflected by
this gold plating layer 77, transmitted through red filter 3, and
returned back into reaction chamber 4. The light that is returned
inside reaction chamber 4 is then reflected by gold plating layers
40 and 41 of the inner walls inside reaction chamber 4, transmitted
through red filter 3, and made incident on photoelectric surface 71
of photomultiplier tube 2, and the generation and multiplication of
photoelectrons are carried out to provide an output in the same
manner as described above.
[0049] The light amount of the light due to chemiluminescence that
is made incident on photoelectric surface 71 of photomultiplier
tube 2 is thus increased by the amount reflected by part of gold
plating layer 77 at the rear surface of first dynode 78a, thereby
improving the sensitivity and enabling the detection of light due
to weak chemiluminescence.
[0050] Also, since photomultiplier tube 2 and reaction chamber 4
are separated and reaction chamber 4 is thus not cooled when
photomultiplier tube 2 is cooled so that the luminescent reaction
is not inhibited, the light due to a luminescent reaction can be
measured at higher sensitivity.
[0051] Gold plating layer 77 on the rear surface of first dynode
78a is high in reflection efficiency so that the loss due to
reflection of the light that is reflected by first dynode 78a and
returns to red filter 3 is low, thus further improving the
detection sensitivity.
[0052] The data on the intensity of the chemiluminescence light
thus obtained by means of photomultiplier tube 2 are analyzed by an
external computing device, etc. (not illustrated) to measure the
concentration of nitrogen monoxide based on the intensity of
chemiluminescence. Here, the intensity of the light due to
chemiluminescence is in a proportional relationship with the
nitrogen monoxide concentration if the amount of ozone in reaction
chamber 4 is adequate, and the nitrogen monoxide concentration can
thus be determined by measuring the intensity of the light.
[0053] This invention's luminescent reaction device/measurement
device is not limited to the embodiment described above.
[0054] For example, the luminescent reaction measured with
luminescent reaction measurement device 1 is not limited to a
reaction of nitrogen monoxide and ozone. For example, besides
nitrogen monoxide, ethylene, isoprene, ammonia, or formaldehyde
(formalin), etc., which reacts with ozone to give rise to
luminescence, may be used as the gas in the sample gas that is
subject to concentration measurement. Also, besides ozone,
fluorine, chlorine, etc., may be used as the oxidizing gas.
[0055] Also, though with the present embodiment, light due to
chemiluminescence is reflected by a part of the rear surface of
first dynode 78a, this invention is not limited thereto and the
light may be reflected by another dynode, such as a ninth
dynode.
[0056] Also, though with the present embodiment, gold plating layer
77 is formed on the rear surface of first dynode 78a to provide a
high light reflecting property, this invention is not limited
thereto as long as the reflectance of the light due to
chemiluminescence is adequately high, and for example, plating of
another noble metal may be used, and depending on the light due to
chemiluminescence, the base material of nickel, etc., may be used
as it is without plating. The same applies to gold plating layers
40 and 41 of the inner walls inside reaction chamber 4 of reaction
module 20, and as long as corrosion resistance is provided and the
light reflectance is high, a plating of another metal may be used
in the same manner, or a member of solid noble metal, etc., may be
mirror polished, etc.
[0057] Also, though with the present embodiment, red filter 3 is
employed as the light transmitting window, this invention is not
limited thereto, and another filter or glass plate, etc., may be
used as long as it transmits the light due to
chemiluminescence.
[0058] Also, though with the present embodiment, Peltier element 76
is equipped as the cooling device and photomultiplier tube 2, in
which just photoelectric surface 71 can be cooled efficiently is
employed, this invention is not limited thereto, and a side-on type
photomultiplier tube and a cooling device that cools the entirety
of this photomultiplier tube may be employed, and even in this
case, since photomultiplier tube 2 and reaction chamber 4 are
separated, reaction chamber 4 will not be cooled and the lowering
of the chemiluminescent reaction rate will not occur. Also, in a
case where the amount of heat generated by a photomultiplier tube
is low, etc., a cooling device does not have to be equipped.
[0059] Industrial Applicability
[0060] This invention can be applied to the concentration
measurement of nitrogen monoxide or other component in a sample
gas.
* * * * *